A memory matrix is segmented in the direction of columns into a plurality of groups of memory cells. The memory cells are accessible through respective preceding word lines each of which is provided for each of the rows of the matrix and commonly to all of the groups of the memory cells and group word lines each of which is provided per group and per row, so that a path for column current is set up during access time only in the column which belongs to a particular group including a particular memory to be accessed.